refactor(config): eliminate ErupeConfig global variable

Replace the mutable global `_config.ErupeConfig` with dependency
injection across 79 files. Config is now threaded through existing
paths: `ClientContext.RealClientMode` for packet encoding, `s.server.
erupeConfig` for channel handlers, and explicit parameters for utility
functions. This removes hidden coupling, enables test parallelism
without global save/restore, and prevents low-level packages from
reaching up to the config layer.

Key changes:
- Enrich ClientContext with RealClientMode for packet files
- Add mode parameter to CryptConn, mhfitem, mhfcourse functions
- Convert handlers_commands init() to lazy sync.Once initialization
- Delete global var, init(), and helper functions from config.go
- Update all tests to pass config explicitly

common/mhfcourse/mhfcourse.go

@@ -1,7 +1,6 @@
 package mhfcourse
 
 import (
-	_config "erupe-ce/config"
 	"math"
 	"sort"
 	"time"
@@ -70,9 +69,9 @@ func CourseExists(ID uint16, c []Course) bool {
 }
 
 // GetCourseStruct returns a slice of Course(s) from a rights integer
-func GetCourseStruct(rights uint32) ([]Course, uint32) {
+func GetCourseStruct(rights uint32, defaultCourses []uint16) ([]Course, uint32) {
 	var resp []Course
-	for _, c := range _config.ErupeConfig.DefaultCourses {
+	for _, c := range defaultCourses {
 		resp = append(resp, Course{ID: c})
 	}
 	s := Courses()